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I'm a well-known mainframe performance guy, with almost 30 years of experience helping customers manage systems. I also dabble in lots of other technology. I've sought to widen the Performance role, incorporating aspects of infrastructural architecture.

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Four score and seven years ago (or so it seems) the Washington Systems Center published a set of mainframe Data-In-Memory studies. These were conducted by performance teams in various IBM labs and were quite instructive and inspiring. I wish I could find the form number (and a fortiori a PDF version) for this book. Anyone? Even hardcopy would be really nice. The reason I mention this is because... [More]

This may be stating the obvious - but I wonder to whom it actually is obvious... I've been doing quite a lot of work with batch job timings and CPU recently. (Everything I'm about to say is equally true of steps.) It's interesting to think about the effects of faster engines versus more engines (a question I haven't been asked recently) and whether a customer needs more capacity or just faster... [More]

It's been almost four years since I wrote DB2 Data Sharing and XCF Job Name .
It mostly stands the test of time but there are a couple of things I want to bring up.
I was in the DB2 Development lab a couple of days ago, talking with a couple of developer friends about DB2 Data Sharing and XCF.
They know DB2 Data Sharing and IRLM much better than I do but XCF not so much.
(It's probable that... [More]

With a couple of working days to go before the deadline I've completed my two presentations for Expo. As usual I've added some new stuff, based on new technologies and some situations I've encountered. And rather than throwing older stuff out I've moved most of it to backup foils. While I'm prepared to present the backup material I don't expect to have time to in the sessions. But at least you'll... [More]

As you probably know Hardware Data Compression has been supported by MVS
and IBM mainframes for around 20 years. In several recent batch studies
I've conducted it's been evident in a widespread way. (In
this post I'm not talking about DB2 compression of either flavour or
VSAM compression - though some of the information here applies to these
functions as well.) It's not as
simple... [More]

Since I got back off vacation in L'Hérault in late August I've been working on adding z10 support to our CPU analysis code. It's quite a substantial set of changes - and I don't think I'm finished yet . But I'd like to share with you what I've learned so far. But first let's briefly review what's changed with z10. (This is a very brief review and not a tutorial on the subjects mentioned.)... [More]

I'm not sure if anyone's done this before. Certainly I've not seen any results... We're beginning to write up some tests the "A Team" (Alain and Pierre) ran before their return to France. Which provides me with some test data. Fortunately I had a stab at mapping the new fields this data contains. One in particular is Stucture CPU (R744SETM)... So, I got to plotting CPU per request against request... [More]

If you think this title is obscure bear in mind the original working title was "Send In The Hobgoblins". 1
When I started to write - actually before the "mind mapping" stage - it was going to be all about inconsistency in the way bits of systems are named. You'll see some of that reflected in the finished article (pun intended) but the post has mostly gone in a... [More]

If you use RMF Postprocessor you won't see this one. If you use Service Units rather than CPU seconds fields in the SMF 72-3 record you also won't see it. It's only if (like me) you use the CPU time for zAAPs in your CPU Utilisation calculation that you'll run into this problem.
If you examine fields R723IFAT (zAAP CPU Time) and R723IFCT (zAAP on GCP CPU Time) you might find them zero when you... [More]

You'd think it would be pretty simple to draw a line. Right?
This post discusses an enhancement I'd like to make to my current reporting - and I'm pretty sure that technically I can do it. The question is whether I should .
Consider my current "Memory by address space within Service Class" graph. Here's a sample:
And here's what I think I might like it to look like:
... [More]

It's been a week since the following was posted in IBM-MAIN: Batch Capacity Planning - BWATOOL? So far there's been no reply. Though a little disappointed, I'm not surprised. "Disappointed" as I was looking for a good debate (even though it wasn't me who asked the question). "Not surprised" as I think the subject of Batch Capacity Planning is a tough one. The original post... [More]

At one level Performance and Capacity Management and Systems Investigation are clearly linked: They share the same data. Or much of it at least.
But I think they're linked in another way, too.
Over the past few years I've gradually shifted emphasis towards Systems Investigation. But this has only been a slight shift, a "non modo sed etiam" and still only really mainframe. So... [More]

I wouldn't want you to decide not to come to Vienna , just because I've made my slides available on Slideshare: I'd hope you'd come to Vienna anyway. It's a great place and it's going to be a great conference. Lots of people can't make Vienna and I don't suppose having the slides to hand is going to tilt the playing field significantly away from coming if you weren't going to anyway. I don't... [More]

I'm working on my presentations for System z Technical University - Vienna, May 2-6 and I'm reviewing the agenda. As well as my four presentations there are lots of other goodies. These range from the Management level down to the purely technical. (I guess mine are towards the latter end of the scale - but I'd say there's lots of pressure on us all to work on cost so detailed information on e.g.... [More]